Key-control telephone switch



n. c. WALKER Ami B.-WEEKS. KEY CONTROL TELEPHONE SWITCH. APPLICATION FILED SEPT. 26, 1921- 1,424,868. Patented ug. 8, 1922 Bo/vzluvo WEEKQS) A TTOR/i/EYS wires DON G. WALKER AND BONZANO WEEKS, 0F.ME1VIPHIS, TENNESSEE.

KEY-CONTROL TELEPHONE SWITCH.

Specification of Letters Patent.

rammed nag. s, 1922.

Application fi1ed September 26, 1921. Serial No.'503,407.

To all whom it may concern: s

Be it known that we, DON O. WVALKER and BoNzANo WEEKS, cltizens of the United States, and residents of Memphis, in the county of Shelby and State of Tennessee, have invented certain new and useful improvements in Key-Control Telephone Switches, of which the. following is a specification.

This invention relates to telephone equip- -ment,and is particularly designed for use in connection with isolated telephone stations,

such as are provided along a railway track -To this end, we provide a'normally open gap in the substation circuit of suflicient dielectric strength to withstand high potential atmospheric discharges, and for closing this gap we provide a key ofa particular construction, thus rendering it impracticable for unauthorized persons to close the circuit and thereby preventing unauthorized use of the instruments.

Referring to the accompanying drawings,

Figure 1 is a perspective view of a casing in which the sub-station equipment is housed,

Figure 2 is a top plan view of the normally open switches in the sub-station circuit and operating mechanism therefor,

Figure 3 is a rear elevation of Figure 2,

Figure 4 is a vertical longitudinal section thereof,

Figure 5 shows a side and end View of a key adapted to operate the device and Figure 6 shows a key guide.

Figure 1 shows an ordinary sub-station boX for housing the transmitting and receiving instruments and their accessories. Supported in this box in any suitable manner is a frame consisting of side plates 2 connected by cross rods 3. Attached to the frame is a horizontal shelf 4 on which are screwed two pairs of spring terminals 5. The members of each pair are normally-out of contact as shown in Figure 4;, being spaced by suitable insulating material. These terminals form a normally open gap in both of the conductors constituting the substation circuit and hence the telephone cannot be used until said terminals'have been moved into contact.

Plvoted on a cross rod supported by the frame is a lever-7 .and attached to the free end thereofis a block'of insulating material 8 extending. across and below the free ends movement of the lever being limit-ed by a cross rod 9. The lever has a curved surface 10 formed intermediately thereof for cooperation wlth a key, as will be described presently. Extending transversely of the frame and attached thereto in any suitable manner is a tubular member 11, having. its axis parallel-with and located somewhat above the aXis of said curved surface 10, the tubular member extending through the side 2 of the frame and registering with a key bushing defining akey hole in the side of the substation box. As clearly shown in Figure 6, the tubular member 11 hasa longitudinal slot 12 extending about halfway thereof and terminating in a wider circumferential slot 13. Supported axially of the member 11is a stem 14 with its free end located'in the key hole of the box. Figure 5. illustrates a type of key of the lower spring terminals, the downward which may be used for operating the device.

As shown, this key is of the ordinary barrel type having a barrel adapted to receive the stem 14 anda prong adapted to slide inthe longitudinal slot of the tubular member and to rotate in the circumferential slot thereof.

To operate the device, one must have a key of the particular construction for which the device is designed. "When desirous of communicating with the central station or headquarters, one having such a key inserts it in thekey hole at the side of the box until the tongue registers with slot 13, in which position the key can be turned to engage the curved surface 10 which being eccentric to the aXis of the key, causes the tongue, when turned, to raise the lever and press the lower spring terminals into firm contact with the upper terminals, closing the circuit and producing a calling signal at the central station. It is necessary to hold the key in circuit closing position during the calling operation and subsequent conversation, for when released the key is returned and the circuit opened by the spring action of the contacts. This, we

regard, as an important advantage of the device, as'it" precludes the possibility of the circuit being accidentally left closed, g

It Will be understood that since the substations to Which our invention is adaptedto be applied are never called from the central station, it is possibletohave a normally open substation circuit Without in any Way impairing the usefulness of the station.

Having: particularly i described the st ructure and mode of operation of our invention,

Whatwerclaim as new: and desire to secure 1.;In= a substation telephone equipment: a

box, for housing the receiving and trans mittingi instruments, frame secured in said heat, two: pairs of insulated leaf springs, the membersofaeach pair being supported on said frame in-spaced superposed relation and: being. connected in the substation circuit so' a's to forma pair of: normally open gaps therein of: sufficient dielectric strength to withstand: high potential atmospheric charges, 'a. lever" f-u lcrumedz on said frame having an: insulating blockfixed on its free end andiextending under the end of the lower naember of each pair of said leaf 'springs,, said. lever having acurved surfaced formed on the lower side thereof, a tubular member. supported transversely of said frame beneath said lever and having a longitudinal slot and a circumferential slot communicating. with the inner end thereof and located opposite the: curved surface of sai'clwlever the 'aXis of said tubular member being parallelwith andsomewhat above the axis ofsaid curved surface, 3 and a stem fixed axially of; said: tubular vmember, said box having a;-key hole in registry With said tubular member for insertion'of a key of the barrel type.

2. In a substation telephone equipment, a

box for housing: the receiving and trans-' terminals, and a key guide extending beneath said lever and in registry with the keyhole in said box.

3. In a substation telephone equipment,

a box for housing the receiving and transmitti-ng instruments, two pairs of spring contact terminals supported in said box, the members ofi'each pair being. supported: in spaced relation and being connected in'the sub-station circuit so as to form a pair of normally open gaps therein. of sufficient dielectric strength to Withstand" high potential atmospheric-charges, and key operated mechanism for holding said: spring terminals into engagement, said spring terminals returning said mechanism to normalv position Wlien the key is released for the purpose described.

4. A, switch for closing. an electric circuit, comprising spaced terminals adapted to same together to establish the circuit, a-lever for moving said terminals into engagement, and a key operated mechanism adapted to move said lever-to bring the terminals to to return, to its initial position hen re leased and thereby opening the circuit.

D N; WALKER- BONZANQ WEEKS,

yield-ingl-y resist movement, for bringing, the

gether and also" adapted to permit the lever 

